It’s darn near impossible to keep up with the changes Facebook makes to your privacy and configuration settings. The latest change is a big one: Facebook just removed everyone’s contact email address from their profiles and replaced it with an @facebook.com address. This was done without asking your permission.
Apparently Facebook’s internal email address – the one they use for notifications and password resets – was not changed, just the one listed on your profile in your Timeline.
Facebook has had its own email since 2010. Almost no one uses it. Presumably this is an attempt to get more people using it. I’m not sure how this change accomplishes this though. I sent a few test messages to my new Facebook email address (I did not have one before) and nothing showed up at either my original Facebook contact address or as a message within Facebook.
Assuming most of you will want to get your old email address back on your profile. This is easy to do. Follow these instructions:

Click “About” on your profile, then scroll down to the Contact info box and click “Edit.” This will open a pop-up dialog box.

Within that pop-up, on the right side, click on the circle next to your Facebook email address and change its setting to “Hidden From Timeline”.

Click on the circle next to your other email addresses and change their settings to “Shown on Timeline”.

While you’re at it, check (and adjust as appropriate) who can see your email addresses.

To save your changes, make sure click the Save button at the bottom of the Edit popup.

I realized I wasn’t displaying my email address… conscious choice there – but this has actually given me the ability to do that – without disclosing my normal, personal email address to the whole-wide world. I display my FB email as “public” and my personal email to “friends”. FB email goes to your messages anyway… so I’ve actually gained from this!